Crankpin turning device



A. s. NEuBAUr-:R

CRANK PIN TURNING DEVICE Sept. 21, 1943.

Filed Nov. 27, 1959 Patented Sept. y 21, 1943 QRANKHN TURNING DEVICE f Aloysius Neubauer, Marble, Minn., assignor of i l n I one-'fourth to Frank B. Colombo and one-fourth to Gerald A. Schedin, Marble, Minn.

" Application November 27, 1939,A Serial No. 306,321

UNITED .STATES eTeNT-i ``o1=1`=ic13 f 2 Claims.

This invention relates to cutting or turning tools and is particularly adapted to tools used for turning crank pins on crank shafts in motorvehicle engines and other power devices.

After a crank shaft hasbeen used for any length of time the crank pin will become worn and will get out of round. This is due to constant and repeated application of forces against the pin only at certain places on the circumference thereof. vThe shaft portions which rotate in the main or stationary bearings lie on the axis of rotation of the crank shaft andthese can be turned down to make them round on an ordinary lathe with the usual turning equipment. This, however, is not true of the crank pins since they are offset from theaxis of the shaft. Certain devices have been developed for reshaping crank pins but there have beenlcertain disadvantages. Some of them comprise tool heads having portions cut out from their edges so that the tools can be slipped over the crank pins. Such tools are frequently operated bylh'a'nd Vand whether they are hand operated or not'they do not encircle the crank pin and there is'insuffcient bearing surfaces around the pin with the result that a cutting element used for turningV thesliaft'will chatter and the cut will not be smooth. Other tools previously developed have utilized Vabrasive materials in the place of cutters.` These are impractical for the reason that the crank pin may be worn to a smaller diameterat oneportion than another along the axis of the pin. The 4abrasive will quickly tend to conform to the improper or v worn shape of the vcrank pinand consequently .crankpin turningltoolv wherein the crank pin will be firmly positioned with respect tothe cutter yet free to rotate so that asmooth -cut on the pin will be secured. Y Y i Another object of the invention is to provide a crank pin turning tool wherein properly distributed bearings are .provided and wherein a tool steel cutteris supported by the head of the tool to eliminate the disadvan'tagesjof tools vutilizing blocks oflabrasive. '1 f v A further object of the invention is to provide an adjustable cutter and micrometric means for indicating extent of adjustment of the cutter and resulting depth of `outA on the pin.

A further object of 'the invention is to provide a crank pin turning tool which'can'be installed in an intemal'combustion engine so that the pin can be turned downwhile the crank shaft is in themotor. 'i l 't These and other objects and advantages of the invention will more fully appear from the following description made in connection with the accompanying drawing, wherein like reference characters will refer to the same parts throughout the views, and, in which: n

Fig. 1 is an .elevation of -my tool showing it in combination with an engine piston, a fragment of a cylinder and a portion of a crank shaft;

Fig. 2 is an enlarged fragmentary elevation of the head of my tool with'a section of a crank shaft taken approximately on the line 2 2 of Fig. 1; g

Fig. 3 is a transverse section taken approximately on the line 3--3 of Fig. 2; 4 y Fig. 4 is a vertical section taken approximately on the line 4-4 of Fig. 2; and t n A Fig. `5 is a bottom plan view.V In Fig. 1 there is shown a portion of a crank shaft 6 with a crank pin 1 about .which the head of my tool is positioned. The head comprisesa pair of separable portions 8 and 9 and extending upwardly from the head portion 8 is a shank l0. The shank at its upper end is provided with an aperture adapted to receive the wrist pin Il of a piston I2 which reciprocates in a cylinderl. The upper end of the tool is not shown in detail since it is merely a vmember with an aperture therethrough and the wrist pin can be loosely receivedin the aperture. If desired, the upper end of the tool may be split asthe lower head is to facilitate connecting of said upper end to the wrist pin.

Referring particularly to Fig. 2 the two too-l head vportions 8 andSdene a relatively large aperture i4 which is adaptedy to receive thecrank pin I. The upper head portion 8 is provided with a block I5 which has a smooth bearing surface exposed in the aperture I4Y and at the right-hand side of the Ahead porticn' is a second bearing block I6 which also has a bearing face exposed in the aperture I4. I It will be seen that the bearing elements land i6 are rigidlyfsupporte'd by the Vtool head ,and that they are positioned degrees blocks areroundedso' that said blocks will fit into the portions of the crank pin muchy in the same manner 'as the ordinary connecting 'rod'bearing Starting with the upper bearing I5 androllowing'around the `aperture I4 ina ckickwise 'direction it will be found that the cutter element I'l is approximately 180 degrees from the iirst bearing block i5 and approximately 90 degrees from the second bearing block I6. In this case as well as in the case of the spacing ofthe two bearing blocks it is not necessarily essential'that the cutter be spaced vand 90 degrees respectively from the bearing blocks l5 and I6, but it has been found that this spacing provides for smooth relative movement between the cutter head and the crank pin so that the cutter element wl not dig into the pin during the cutting operation. Furthermore, this spacing Ahas resulted in elimination of the tendency in other tools to accentuate the out of roundness oi the crank pin.

Positioned rearwardly of the cutter and approximately 45 degrees thererom and Vsi-ibstantially opposite to the mid-'point between the bearing blocks I 5 and I6 is a resilient'bearingelement I8 This element as can be seen .islclarnped between the two halves of the cutter head with a portion extending into the aperture I d at `an angle constituting a chord \of the circle described by said aperture. The 1dotted 4.line .position of -the resilient I8 is the .position with no crank .pin .in the tool .and lthe :full line ,position of the resilient or free .end of the bearing I8 is `that position when .the .bearing `is pressing against the crankpin 5. It will 4be seen that .the lresilient bearing `I8 presses the cran-k V`pin upwardly on a diagonal and keeps the rigidly mounted bearings I5 .and l5 .in `contact rath the crank pin at all times.

rEhe cutter `I-'I .is mounted :for axial sliding movement in the lower portion 9 of the -tool head and the bottom of said cutter extends `into a bore 19 which is formed .in a downward .extension 29 alt lthe bottom of the tool .head section -9. yA .plug or follower `2II is threadedintothe bore I9 as indica'ted in Fig. 2, and the inner end of .said .plug bears against the bottom of the cutter I l.. The .plug .2J is provided with .a keri 22 so that it .can be rotated with a screw driver or .similar tool. Around the lower edge o [the downward exten- -sion `2ll vI 4prov-ide a series Yol vgraduations indicated .at T23 andon the bottom end of the Aplug 2l .is an'arrow or other suitable indicator .2'4 which in .combination with the .graduations 23 indica'tes the amount of axialadjustment of the plug 2l and .cutter Il rIhus .it is .possible to -accurately gauge the amount of metal taken .off of .the crank .pin dur-ing the reshaping operation. .The .graduations and arrow thus ,provide a micrometric indicator 'for the depth and extension of cut.

'When the device used an internal -combuston engine the connection of the `upper end of the .tool shank I D tothe wrist pin II provides .a 4guide `for the tool which is sui'iciently stable .to insure accurate and smooth cutting. 'As stated above, it is not necessary, however, to closely 't the wrist .pin in the .upper .end lof the tool .since -the working of the piston I2 in the cylin- .der I3 aor'ds .a sufficiently .smooth guide to .pro-

vide for extremely accurate and even cutting.`

As a .matter of fact, .it .is -possible to turn down a crank pin on a -lathe with .my .tool by securing the .head around the crank .pin and ,permitting .the other end ofi the .shank to slide back .and forth -over a smooth plate positioned on .the lathe bed. With such an .arrangement the plate would -be positioned 4tothe .right of the appara- .tus as viewed .in Fig. 2 andthe clockwise movement -of the crank vpin relative to .the tool head and the .drag .produced by .the outterin .its work will keep the other -end .of the .tool .in .constant 'contact with a .bearing plate .such as .I .have described. -during rotation of the `crank .pin which :in .conjunction with .the crank .pin bearing .arrangement .produces a Asmooth .cut without the chattering incident lto `those hand operated tools It 'is this continuous -pressure exerted' heretofore used wherein the tool head is provided with a generally U-shaped cut out from one edge. Furthermore, the relationship between the various bearing contacts and the cutter `will produce a cut which will take oi high spots and produce a truly round cut whereas in the old types referred to it is not possible to secure the proper bearing distribution and tool guiding to secure a properly rounded cut.

It is unnecessary to provide tools of different lengths for each length of crank shaft throw and connecting rod measurement since the piston is not being operated under its normal conditions and it acts merely as a guide and can reciprocate through a different stroke than the ordinary engine vstroke without` effecting operation of the tool. VIt has been found that the crank shaft .can be turned .by hand or it has even- `been found possible to restore crank pins to roundness by installing the tool in Athe engine and rotating the shaft with a conventional engine starter.

In addition to the .fact .that a cutting tool will cu't to the desired shape and .not conform :to .the shape of fthe crank shaft as in the case of abrasive tools the. operation is materially speeded up. In many cases it has been found that the `crank shaft need be rotated no more than twelve to .dfteen times and that the finished cut .is .suiciently smooth to render polishing of the crank pin unnecessary. y

It will, of course, be understood that various changes .may be made 4in .the form, details, .arrangement and proportions of the various part-s without departing from the scope of Amy .invention. i i

What is claimed is:

1. A crank pin turning tool comprising, a head made up of a Apairo separable .portions and having means .for tightlyclamping them .together about `a crank pin, a cutter carried by a portion of said head, bearing .elements carried yby said head and adaptedto guide said .crank ypin. when being operated on by said cutter,` and a resilient bearing member adapted to keep said .first mentioned bearing elements in contact with said pin. said resilient bearing member including a relatively thin `hat portion having a side face positioned to engage said crank pin, and said resilient bearing member including another portion positioned between and clamped by the Vsepara- 'ble portions of the head of saidtooh '2. A crank pin turning tool comprising, a head portion made up of a pair o'f separable parts and shaped to t relatively Yclosely around a crank pin, a cutter, member supported 'by 'one part of said head and 'extending inwardly therefrom to engage a crank p'in receivedby said vloeeuthcrank pin bearing elements supportedby said lhead and positioned 5to engage said pin 'to hold said pin 'and head in :proper relative positions for cutting` and a resilient bearing member carried by said `head and adapted to lengage a .portion of said -pin 'opposite said'rst mentioned bearing ele- -ments to force saidp'in'toward rsaid first mentioned bearing elements, said resilient bearing member `having aV at portion of considerable surface area and adapted to lie 4tangentially of said crank pin while in engagement therewith, and said resilient bearing member 'having an anchoring portion positioned between Said tool .head parts and secured thereby. 1

.ALOYSIUS S. fNEUBAUER. 

